Patch hole in hull - cut beyond frame?

Discussion in 'Metal Boat Building' started by Constant Refit, Jul 25, 2018.

  1. Constant Refit
    Joined: Jul 2018
    Posts: 1
    Likes: 0, Points: 1
    Location: Portugal

    Constant Refit New Member

    My first post. And first patch!
    Not a great pic, but this is looking down on the port side aft, stern at the top of the pic. Looks like there's still plenty of steel right next to the frame and the stringer , should I cut the old plate beyond the frame/stinger and weld in a patch? Slowly talking myself into this being a good idea but would welcome any experience. Also, the original steel is 4mm, I've found a bit of 6mm plate - should I do the rounds locally on the trusty foldup bike (full time liveaboard) and get some 4mm?

    Not been welding that long so ready to ask for help or get someone with lots experience in if it starts to go wrong, but sooner or later I might be on my own so gonna give it a go - any hints or links as to ideal gap , how much bevel & general tips?

    Thanks!! :)

  2. gonzo
    Joined: Aug 2002
    Posts: 16,354
    Likes: 1,407, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    That plate seems to have lost maybe 60% of the material in some areas. Sometimes the only way to weld a patch in those conditions is to first weld a backing plate (maybe 10 times the thickness of the plating for width) behind the seam. Otherwise, if you don't mind the looks, they get welded overlapping the hole.
  3. MikeJohns
    Joined: Aug 2004
    Posts: 3,192
    Likes: 208, Points: 63, Legacy Rep: 2054
    Location: Australia

    MikeJohns Senior Member

    See if you can get somone to show you how to weld or at least tell you what you are doing right and wrong.

    At 4mm you need a MIG , and I'd stick to the same plating thickness. I'd replace the longitudinal too and take out more plating, it's very little extra work. Try and round the corners of the hole for best practice but small boats are quite forgiving of poor construction practices.
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.